# Resistors in seriess-current is the same?

• oneplusone
In summary: A current is the flow of electrons through a conductor. In a simple circuit, like the one shown above, current is the same whether the conductors are in series or in parallel. The current flows through the circuit the same way, but the voltage is different.In a series circuit, like the one shown above, the voltage is the same at each conductor. So the current flowing into each conductor is the same. The current flowing out of each conductor is also the same. However, the voltage is different. The voltage across each resistor is the same, but the voltage across the battery is different.
oneplusone
resistors in seriess---current is the same??

So current is the same if you have resistors in series….but won't the current decrease because the resistors provide resistance to the current??\

Isn't current inversely proportional to resistance for a set voltage? I mean, adding up the resistance of resistors in series is just R(total) = r1 + r2 + r3 but that doesn't change anything about Ohm's law. You would have to add more voltage to get the same current flow. (I would think)

Question is not clear but I interpret it as being about why when two resistors - say R1 and R2 - are in series the current through R1 is the same as the current through R2. If they were different than some of the electrons passing through R1 would not pass through R2. Where do you suppose they would go? If I were to connect two straws in series than it might get harder for me to pump water through them - increased resistance - and the flow of water - the current - would decrease. But the flow through the first straw would be the same as the flow through the second straw. Otherwise where do we suppose the water would go? If I increase the pressure difference between the ends of the straw - increased voltage - the flow of water through the straw increases - increased current. That's the essence of Ohm's law.

But isn't current coulombs per second?? So it measures the rate at which the current is flowing? So wouldn't the resistor "hold back" some charge, making it slow down --> less current

oneplusone said:
But isn't current coulombs per second?? So it measures the rate at which the current is flowing? So wouldn't the resistor "hold back" some charge, making it slow down --> less current

No, the resistor doesn't hold back any charge. All the charge that goes in at one end comes out at the other end. It just takes longer to get there. Just as all the water that goes in at one end of a straw comes out at the other end. If you squeeze the straw - increasing the resistance - all the water that goes in still comes out at the other end, but it takes longer to get there.

dauto said:
No, the resistor doesn't hold back any charge. All the charge that goes in at one end comes out at the other end. It just takes longer to get there. Just as all the water that goes in at one end of a straw comes out at the other end. If you squeeze the straw - increasing the resistance - all the water that goes in still comes out at the other end, but it takes longer to get there.

That isn't a very good analogy because, as you said, it takes the water more time to go through the straw, making the current q/s, smaller. Even so, the resistor doesn't "slow down" the current when the circuit is in equilibrium.

Edit: +1 on post #3

TheDemx27 said:
That isn't a very good analogy because, as you said, it takes the water more time to go through the straw, making the current q/s, smaller. Even so, the resistor doesn't "slow down" the current when the circuit is in equilibrium.

Edit: +1 on post #3

It is an excellent analogy. You must've misunderstood post #3. The resistor does slow down the motion of the electrons reducing the current just as a constriction in a straw slows down the flow of water.

oneplusone said:
So current is the same if you have resistors in series….but won't the current decrease because the resistors provide resistance to the current??\

The current flowing into a resistor is the same as the current flowing out - only the voltage changes, which is the essence of Ohm's Law: voltage drop = current x resistance.

So if you put two resistors in series the current remains the same.

You can understand this in terms of "where does the charge go?" - capacitors store charge, but resistors (ideal resistors) don't ... hence every bit of charge entering must exit.

Remember, a wire is also a resistor ... they may have a low resistance, but it is cumulative over the length of a wire.

dauto said:
It is an excellent analogy. You must've misunderstood post #3. The resistor does slow down the motion of the electrons reducing the current just as a constriction in a straw slows down the flow of water.

what if i tell you it doesn't ? well usually it does but not necessarily , actually in circuits with different resistors , current flows faster through resistors of low Cross section area , to maintain a steady current , anyway its NOT about speed of electrons
back to OP
the way i like to think about it is as follows
imagine a train that is composed of 3 carriages , as the train was moving , you exert a force in the carriage in the middle that slows it down * let's for the sake of our argument consider the velocity of the train to be analogous to the current intensity * anyway , as you slow down the carriage in the middle , what is going to happen ?
since the carriages are connected with some bond that can neither expand nor compress
once you slow down the carriage in the middle the carriage will slow down the other carriages , the force will be propagated quickly to the carriage in frfont of it and the carriage behind it , slowing them down just as much as the carriage in the middle was slowed down , thus the train carriages keep moving with the same velocity
now back to the current point of view
forgive me for connecting ideas of current and velocity but it was just to serve the purpose of the analogy , anyway
in the current , suppose you have 3 resistors , then a fourth resistor appear out of no where , what is going to happen is that at the point where the charges enter this 4th resistor , the current will decrease at this point where it is forced to enter a resistor , thus causing a build up of charge that happens in an infinitesimal amount of time , this build up of charges pushes the charges behind it , and these charges push the charges behind them and it goes on to the start point of the circuit .
of course all of this happens in very small amount of time that is too small to be noticed .
just like the 3 carriages , if you slow down the first carriage , it will cause the coupling between the first carriage and the second one to compress , and of course since the coupling is sturdy it will not be compressed * or it might compress for a very small amount of time * so the force propagates through the coupling and slow down the second carriage , and the same happens to the third carriage .
hope this helped

btw in this analogy , the coupling is analogous to the electric force between electrons
and in case you didnt know what a coupling is
http://en.wikipedia.org/wiki/Railway_coupling

oneplusone said:
So current is the same if you have resistors in series….but won't the current decrease because the resistors provide resistance to the current??\
It sounds like you're confusing two different situations. In a given circuit, if two resistors are in series, the current through the first resistor is the same as the current through the second resistor. You, however, are thinking of two different circuits, one with only one resistor and a second circuit in which you add a resistor in series with the first resistor. In this case, yes, the current decreases because the total resistance increases.

KingCrimson said:
btw in this analogy ...

Analogies 'mon cerveau fait mal'.

## 1. What is a resistor and how does it work in a series circuit?

A resistor is an electronic component that restricts the flow of electricity. In a series circuit, resistors are connected in a single path and the current flowing through them is the same. This means that the current is not divided among the resistors, but instead, the same amount of current flows through each resistor.

## 2. How does the current stay the same in a series circuit with multiple resistors?

In a series circuit, the current stays the same because there is only one path for the electricity to flow through. As the current flows through each resistor, it experiences a drop in voltage, which results in a decrease in the current. However, since there is only one path, the current must be the same at all points in the circuit.

## 3. What happens to the voltage across each resistor in a series circuit?

In a series circuit, the voltage across each resistor adds up to the total voltage of the circuit. This means that the voltage across each resistor is proportional to its resistance. For example, if there are two resistors in series with resistance values of 50 ohms and 100 ohms, the voltage across the 50 ohm resistor will be half of the total voltage, while the voltage across the 100 ohm resistor will be twice the total voltage.

## 4. Can the total resistance of a series circuit be calculated?

Yes, the total resistance of a series circuit can be calculated by adding the individual resistances together. This is known as the series resistance rule. For example, if there are three resistors in series with values of 10 ohms, 20 ohms, and 30 ohms, the total resistance would be 60 ohms (10 + 20 + 30 = 60).

## 5. How does the total resistance affect the current in a series circuit?

The total resistance of a series circuit has an inverse relationship with the current. This means that as the total resistance increases, the current decreases. This is because with a higher resistance, there is more opposition to the flow of current, resulting in a lower current. Conversely, if the total resistance decreases, the current increases.

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